Many prior art systems are known for dynamically allocating green light time of a traffic light for enabling free passage of a vehicle through a given intersection.
For example, U.S. Pat. No. 7,557,731 discloses a system and method for regulating the flow of traffic at a roadway intersection having one or more traffic signals by positioning a processor in the vicinity of the intersection to store cycle times of the traffic flow directions, mounting an RFID reader in the vicinity of each traffic signal in communication with the processor, mounting a plurality of RFID tags in the vicinity of a license plate so as to be within the communication range of an RFID reader at the intersection and so that the RFID readers interrogate the RFID tags of the vehicles, calculating an unused time slice of the cycle time for at least one of the traffic flow directions at the intersection; and, reducing the cycle time for the traffic flow.
Likewise JP 2004013199, JP 2004287983, JP 2005352615, JP 2008102738, KR 20040022306, US 2002/0145541, US 2006/0202862, US 2008/0150759 and US 2009/0231160 also disclose a system for regulating the flow of traffic by means of a radio transceiver mounted in the vicinity of an intersection and a radio transceiver mounted on a vehicle.
These prior art systems are only capable of accurately determining that no vehicles are located in a particular lane approaching the intersection and to allocate the flow of traffic accordingly: however, these prior art systems incapable of accurately determining how many vehicles are waiting in line at a given intersection since many intersections in urban areas are spaced from each other by a distance of 50-100 m, a distance which is in the range of an RFID reader. Thus the prior art systems may arrive at an incorrect conclusion that some vehicles are located at an intersection and allocate green light time of the traffic light at that intersection in response to the incorrect conclusion, while in reality those vehicles are located at an adjacent intersection. On the other hand, the RFID reader will not be able to be able to receive information from all of the vehicles at a given intersection if its range is excessively short.
The prior art systems are also liable to arrive at an incorrect conclusion when receiving a signal that originated from a mobile device of a pedestrian or of a bus passenger or the like located at the given intersection.
It is an object of the present invention to provide a system and method for accurately determining the number of vehicles that are approaching an intersection in each direction.
It is an additional object of the present invention to provide a system and method for dynamically and accurately allocating green light time of a traffic light at a given intersection.
It is an additional object of the present invention to provide a system and method for accurately allocating green light time of a traffic light at a given intersection while disregarding signals transmitted from pedestrians or motor vehicle passengers.
Other objects and advantages of the invention will become apparent as the description proceeds.